Display apparatus, drive circuit, driving method and electronic apparatus

ABSTRACT

A display apparatus includes: a display device; a touch detection device; and a driver unit driving the display device so as to sequentially display M horizontal lines in each of plural unit drive periods forming one frame period and driving the touch detection device in N touch detection periods provided in each unit drive period, in which N is lower than M.

CROSS REFERENCES TO RELATED APPLICATIONS

The present application is a continuation of U.S. application Ser. No.15/412,594, filed Jan. 23, 2017, which is a continuation of U.S.application Ser. No. 14/824,829, filed Aug. 12, 2015, issued as U.S.Pat. No. 9,588,631 on Mar. 7, 2017, which application is a continuationof U.S. application Ser. No. 13/645,179, filed Oct. 4, 2012, issued asU.S. Pat. No. 9,141,222 on Sep. 22, 2015, which application claimspriority to Japanese Priority Patent Application JP 2011-224536 filed inthe Japan Patent Office on Oct. 12, 2011, the entire content of which ishereby incorporated by reference.

BACKGROUND

The present disclosure relates to a display apparatus having a touchdetection function, a drive circuit, a driving method and an electronicapparatus having such display apparatus.

In recent years, a display apparatus attracts attention, in which atouch detection device which is a so-called touch panel is mounted on adisplay panel such as a liquid crystal display device or the touch paneland the display panel are integrated and various button images and thelike are displayed on the display panel to thereby enable informationinput instead of normal mechanical buttons. As an input device such as akeyboard, a mouse or a keypad is not necessary in such display apparatushaving the touch panel, the display apparatus tends to be widely usednot only in a computer but also in portable information terminals suchas a cellular phone.

There are some touch-panel systems such as an optical type and aresistive type, and a capacitance-type touch panel having a relativelysimple structure as well as capable of realizing low-power consumptionis requested. For example, there is proposed, in JP-2009-244958 (PatentDocument 1), a display apparatus with a so-called in-cell type touchdetection function in which a common electrode for display originallyarranged in a display panel is also used as one of a pair of electrodesfor a touch sensor, and the other electrode (touch detection electrode)is arranged so as to intersect with the common electrode. There are alsoproposed some so-called on-cell type display apparatuses with the touchdetection function in which a touch panel is formed on a display surfaceof the display panel.

SUMMARY

There is a case in which, for example, display operation and touchdetection operation are performed in synchronization with each other inthe above display apparatus. In such case, there is a danger that thedegree of freedom in the touch detection operation is reduced as thetouch detection operation is constrained by the display operation.

In view of the above, it is desirable to provide a display apparatus, adrive circuit, a driving method and an electronic apparatus capable ofincreasing the degree of freedom in touch detection operation.

An embodiment of the present disclosure is directed to a displayapparatus including a display device, a touch detection device, and adriver unit. The driver unit drives the display device so as tosequentially display M horizontal lines in each of plural unit driveperiods forming one frame period and drives the touch detection devicein N touch detection periods provided in each unit drive period, inwhich N is lower than M.

Another embodiment of the present disclosure is directed to a drivecircuit including a driver unit driving the display device so as tosequentially display M horizontal lines in each of plural unit driveperiods forming one frame period and driving the touch detection devicein N touch detection periods provided in each unit drive period, inwhich N is lower than M.

Still another embodiment of the present disclosure is directed to adriving method including driving the display device so as tosequentially display M horizontal lines in each of plural unit driveperiods forming one frame, and driving the touch detection device in Ntouch detection periods provided in each unit drive period, in which Nis lower than M.

Yet another embodiment of the present disclosure is directed to anelectronic apparatus including the display apparatus described above.The electronic apparatus corresponds to a television apparatus, adigital camera, a personal computer, a video camera, portable terminaldevices such as a cellular phone, and the like.

In the display apparatus, the drive circuit, the driving method and theelectronic apparatus according to the embodiments of the presentdisclosure, display driving with respect to M horizontal lines issequentially performed in the unit drive period. In the operation, thetouch detection device is driven in the N touch detection periodsprovided in the unit drive period, in which N is lower than M.

In the display apparatus, the drive circuit, the driving method and theelectronic apparatus according to the embodiments of the presentdisclosure, the touch detection device is driven in the N touchdetection periods provided in the unit drive period, in which N is lowerthan M, therefore, the degree of freedom in touch detection operationcan be increased.

Additional features and advantages are described herein, and will beapparent from the following Detailed Description and the figures.

BRIEF DESCRIPTION OF THE FIGURES

FIGS. 1A and 1B are views for explaining basic principles of a touchdetection system in a display panel according to an embodiment of thepresent disclosure, showing a state where a finger does not touch ordoes not come close to the display panel;

FIGS. 2A and 2B are views for explaining basic principles of the touchdetection system in the display panel according to the embodiment of thepresent disclosure, showing a state where a finger touches or comesclose to the display panel;

FIGS. 3A and 3B are views for explaining basic principles of the touchdetection system in the display panel according to the embodiment of thepresent disclosure, showing an example of waveforms of a drive signaland a touch detection signal;

FIG. 4 is a block diagram showing a configuration example of the displaypanel according to the embodiment of the present disclosure;

FIG. 5 is a block diagram showing a configuration example of a selectionswitch unit shown in FIG. 4;

FIG. 6 is a cross-sectional view showing a schematic cross sectionalstructure of a display device with a touch detection function shown inFIG. 4;

FIG. 7 is a circuit diagram showing pixel arrangement in the displaydevice with the touch detection function shown in FIG. 4;

FIG. 8 is a perspective view showing a structure example of driveelectrodes and touch detection electrodes in the display device with thetouch detection function shown in FIG. 4;

FIGS. 9A to 9C are schematic views showing an example of touch detectionscanning in the display panel shown in FIG. 4;

FIGS. 10A to 10F are timing charts showing an operation example of adisplay panel according to a first embodiment of the present disclosure;

FIGS. 11A and 11B are waveform charts showing waveform examples of an ACdrive signal and a touch detection signal according to the firstembodiment of the present disclosure;

FIGS. 12A and 12B are timing waveform charts showing touch detectionscanning according to the first embodiment of the present disclosure;

FIGS. 13A to 13D are waveform charts showing an example of touchdetection operation according to the first embodiment of the presentdisclosure;

FIGS. 14A and 14B are timing charts showing an operation example of adisplay panel according to a modification example of the firstembodiment;

FIGS. 15A and 15B are timing charts showing an operation example of adisplay panel according to another modification example of the firstembodiment;

FIGS. 16A to 16H are timing charts showing an operation example of adisplay panel according to further another modification example of thefirst embodiment;

FIGS. 17A to 17D are timing charts showing an operation example of adisplay panel according to further another modification example of thefirst embodiment;

FIGS. 18A to 18D are waveform charts showing waveform examples of ACdrive signals and touch detection signals according to a secondembodiment of the present disclosure;

FIGS. 19A to 19C are waveform charts showing an example of touchdetection operation according to the second embodiment of the presentdisclosure;

FIGS. 20A to 20D are waveform charts showing another example of thetouch detection operation according to the second embodiment of thepresent disclosure;

FIGS. 21A and 21B are timing waveform charts showing touch detectionscanning according to a modification example of the second embodiment;

FIGS. 22A to 22F are waveform charts showing waveform examples of ACdrive signals and touch detection signals according to a thirdembodiment of the present disclosure;

FIGS. 23A and 23B are timing charts showing an operation example of adisplay panel according to a fourth embodiment of the presentdisclosure;

FIGS. 24A to 24F are timing charts showing an operation example of adisplay panel according to a fifth embodiment of the present disclosure;

FIG. 25 is a perspective view showing an external structure of anapplication example of the display panel to which the embodiment isapplied;

FIGS. 26A to 26C are schematic views showing an example of touchdetection scanning in a display panel according to a modificationexample;

FIGS. 27A and 27B are waveform charts showing waveform examples of an ACdrive signal and a touch detection signal according to anothermodification example; and

FIGS. 28A and 28B are waveform charts showing waveform examples of an ACdrive signal and a touch detection signal according to further anothermodification example.

FIG. 29 is a cross-sectional view showing a schematic cross sectionalstructure of a display device with a touch detection function accordingto further another modification example.

DETAILED DESCRIPTION

Hereinafter, embodiments of the present disclosure are explained indetail with reference to the drawings. The explanation will be made inthe following order.

-   1. Basic Principles of Capacitance-Type Touch Detection-   2. First Embodiment-   3. Second Embodiment-   4. Third Embodiment-   5. Fourth Embodiment-   6. Fifth Embodiment-   7. Application Examples

<1. Basic Principles of Capacitance-Type Touch Detection>

First, basic principles of touch detection in a display panel accordingto an embodiment of the present disclosure will be explained withreference to FIGS. 1A to 3B. A touch detection system is embodied as acapacitance-type touch sensor, in which, for example as shown in FIG.1A, a pair of electrodes (a drive electrode E1 and a touch detectionelectrode E2) arranged opposite to each other so as to sandwich adielectric D are used to form a capacitor device. This structure isrepresented as an equivalent circuit shown in FIG. 1B. The driveelectrode E1, the touch detection electrode E2 and the dielectric Dconfigure a capacitor device C1. One terminal of the capacitor device C1is connected to an AC signal source (drive signal source) S and theother terminal P is grounded through a resistor R as well as connectedto a voltage detector (touch detection circuit) DET. When an ACrectangular wave Sg (FIG. 3B) of a given frequency (for example,approximately several kHz to several dozen kHz) is applied from the ACsignal source S to the drive electrode E1 (one terminal of the capacitordevice C1), an output waveform (touch detection signal Vdet) as shown inFIG. 3A appears at the touch detection electrode E2 (the other terminalP of the capacitor device C1). The AC rectangular wave Sg corresponds toan AC drive signal VcomAC which will be described later.

In a state where a finger does not touch (or is not close to) thesensor, a current I0 corresponding to a capacitance value of thecapacitor device C1 flows with charge/discharge to the capacitor deviceC1 as shown in FIG. 1B. A potential waveform of the other terminal P ofthe capacitor device C1 at this time is, for example, as shown by awaveform V0 of FIG. 3A, which is detected by the voltage detector DET.

On the other hand, in a state where a finger touches (or is close to)the sensor, a capacitor device C2 formed by the finger is added to thecapacitor device C1 in series as shown in FIG. 2B. In this state,currents I1 and I2 respectively flow with charge/discharge to thecapacitor devices C1 and C2. A potential waveform of the other terminalP of the capacitor device C1 is, for example, as shown by a waveform V1in FIG. 3A, which is detected by the detector DET. At this time, apotential of the point P is a divided potential fixed by values of thecurrents I1 and I2 flowing in the capacitor devices C1 and C2.Accordingly, the waveform V1 will be a lower value than the waveform V0in the non-contact state. The voltage detector DET compares the detectedvoltage to a given threshold voltage Vth and determines the state as thenon-contact state when the detected voltage is equal to or higher thanthe threshold voltage, whereas determines the state as the contact statewhen the detected voltage is lower than the threshold voltage. The touchdetection can be performed in the above manner.

2. First Embodiment Configuration Example Entire Configuration Example

FIG. 4 shows a configuration example of a display panel according to anembodiment. A display panel 1 is a so-called in-cell type displayapparatus in which a liquid crystal display panel and a capacitance-typetouch panel are integrally formed.

The display panel 1 includes a control unit 11, a gate driver 12, asource driver 13, a selection switch unit 14, a drive electrode driver16, a display device with a touch detection function 10 and a touchdetection unit 40.

The control unit 11 is a circuit supplying control signals to the gatedriver 12, the source driver 13, the drive electrode driver 16 and thetouch detection unit 40 respectively based on a video signal Vdisp andcontrolling these units to operate in synchronization with one another.In the operation, the control unit 11 controls these circuits so that atouch detection period Pt is provided once every time a liquid crystaldisplay device 20 of the display device with the touch detectionfunction 10 displays horizontal lines of two rows as described later.

The gate driver 12 has a function of sequentially selecting onehorizontal line to be a target of display driving in the display devicewith the touch detection function 10 based on the control signalsupplied from the control unit 11. Specifically, the gate driver 12applies a scanning signal Vscan to gates of TFT devices Tr of pixels Pixthrough scanning signal lines GCL to thereby sequentially select one row(one horizontal line) as a target of display driving in the pixels Pixformed in matrix in the liquid crystal display device 20 of the displaydevice with the touch detection function 10 as described later.

The source driver 13 generates and outputs a pixel signal Vsig based onthe video signal and the control signal supplied from the control unit11. Specifically, the source driver 13 generates the pixel signal Vsigobtained by performing time-division multiplexing to pixel signals Vpixof plural (three in this case) sub-pixels SPix in the liquid crystaldisplay device 20 of the display device with the touch detectionfunction 10 from the video signal for one horizontal line and suppliesthe signal to the selection switch unit 14 as described later. Thesource driver 13 also has a function of generating switch controlsignals Vsel (VselR, VselG and VselB) necessary for separating the pixelsignals Vpix multiplexed into the pixel signal Vsig and supplies thesignals to the selection switch unit 14 with the pixel signal Vsig. Themultiplexing is performed for reducing the number of wiring between thesource driver 13 and the selection switch unit 14.

The selection switch 14 separates the pixel signals Vpix which have beentime-division multiplexed into the pixel signal Vsig based on the pixelsignal Vsig and the switch control signals Vsel supplied from the sourcedriver 13 and supplies the signals to the liquid crystal display device20 of the display device with the touch detection function 10.

FIG. 5 shows a configuration example of the selection switch unit 14.The selection switch unit 14 includes plural switch groups 17. Eachswitch group 17 has three switches SWR, SWG and SWB in this example, inwhich respective one of terminals are connected to one another and thepixel signal Vsig is supplied from the source driver 13, and in whichthe other terminals are connected to three sub-pixels SPix (R, G and B)relating to the pixel Pix respectively through the pixel signal linesSGL of the liquid crystal display device 20 of the display device withthe touch detection function 10. The three switches SWR, SWG and SWB arerespectively on/off controlled by the switch control signals Vsel(VselR, VselG and VselB) supplies from the source driver 13. Accordingto the above function, the selection switch unit 14 sequentially changesover the three switches SWR, SWG and SWB in a time division manner toturn on these switches in accordance with the switch control signalsVsel, thereby functioning so as to separate the pixel signals Vpix(VpixR, VpixG and VpixB) from the multiplexed pixel signal Vsig. Then,the selection switch unit 14 supplies these pixel signals Vpix to thethree sub-pixels SPix respectively.

The drive electrode driver 16 is a circuit supplying a drive signal Vcomto drive electrodes COML (described later) of the display device withthe touch detection function 10 based on the control signal suppliedfrom the control unit 11. Specifically, the drive electrode driver 16applies a DC drive signal VcomDC to the drive electrodes COML in adisplay period Pd as described later. The drive electrode driver 16 alsoapplies an AC drive signal VcomAC to the drive electrodes COML to be atarget of touch detection operation in the touch detection period Pt andapplies the DC drive signal VcomDC to the drive electrodes COML otherthan the target as described later. The AC drive signal VcomAC includestwo pulses in this example. The drive electrode driver 16 drives thedrive electrodes COML in units of blocks (later-described driveelectrode blocks B) each including a given number of drive electrodesCOML as described later.

The display device with the touch detection function 10 is a displaydevice having the touch detection function. The display device with thetouch detection function 10 has the liquid crystal display device 20 anda touch detection device 30. The liquid crystal display device 20 is adisplay device using a liquid crystal device LC (described later) as adisplay device, which is a device having resolution (960 pixels×540pixels) of qHD (Quarter High Definition) in this example. The resolutionis not limited to the resolution but other resolutions can be applied.The liquid crystal display device 20 is a device performing display bysequentially scanning horizontal lines one by one in accordance with thescanning signal Vscan supplied from the gate driver 12 as describelater. The touch detection device 30 operates based on theabove-described basic principles of the capacitance-type touch detectionand outputs the touch detection signal Vdet. The touch detection device30 performs touch detection by performing sequential scanning inaccordance with the AC drive signal VcomAC supplied from the driveelectrode driver 16 as described later.

The touch detection unit 40 is a circuit detecting whether the touchdetection device 30 has been touched or not based on the control signalsupplied from the control unit 11 and the touch detection signal Vdetsupplied from the touch detection device 30 of the display device withthe touch detection function 10 and calculating coordinates in the touchdetection area when the device has been touched. The touch detectionunit 40 includes an LPF (Low Pass Filter) unit 42, an A/D converter 43,a signal processing unit 44, a coordinate extraction unit 45 and adetection timing control unit 46. The LPF unit 42 is a low-pass filterwhich removes high frequency components (noise components) included inthe touch detection signal Vdet supplied from the touch detection device30 and takes out touch components to thereby output these componentsrespectively. Resistances R for giving DC potential (for example, 0V)are connected between respective input terminals and grounds. The A/Dconverter 43 is a circuit for sampling an analog signal outputted fromthe LPF unit 42 and converting the signal into a digital signalrespectively at timings in synchronization with the AC drive signalVcomAC. The signal processing unit 44 is a logic circuit for detectingwhether the touch detection device 30 has been touched or not based onthe output signal of the A/D converter 43. The coordinate extractionunit 45 is a logic circuit for calculating coordinates in the touchpanel when the touch has been detected in the signal processing unit 44.The detection timing control unit 46 has a function of controlling thesecircuits to operate in synchronization with one another.

(Display Device with Touch Detection Function 10)

Next, a configuration example of the display device with the touchdetection function 10 will be explained in detail.

FIG. 6 shows an example of a cross-sectional structure of a relevantpart of the display device with the touch detection function 10. Thedisplay device with the touch detection function 10 includes a pixelsubstrate 2, a counter substrate 3 arranged opposite to the pixelsubstrate 2 and a liquid crystal layer 6 inserted between the pixelsubstrate 2 and the counter substrate 3.

The pixel substrate 2 includes a TFT substrate 21 as a circuitsubstrate, the drive electrodes COML and pixel electrodes 22. The TFTsubstrate 21 functions as the circuit substrate on which various typesof electrodes and wiring, thin film transistors (TFT) and the like areformed. The TFT substrate 21 is made of, for example, glass. The driveelectrodes COML are formed on the TFT substrate 21. The drive electrodesCOML are electrodes for supplying a common voltage to plural pixels Pix(described later). The drive electrodes COML function as common driveelectrodes for liquid crystal display operation as well as function asdrive electrodes for touch detection operation. An insulating layer 23is formed over the drive electrodes COML and the pixel electrodes 22 areformed thereon. The pixel electrodes 22 are electrodes for supplying thepixel signal Vpix, having transparency. The drive electrodes COML andthe pixel electrodes 22 are made of, for example, ITO (Indium TinOxide).

The counter substrate 3 includes a glass substrate 31, color filters 32and touch detection electrodes TDL. The color filters 32 are formed onone surface of the glass substrate 31. The color filters 32 are formedby regularly arranging, for example, three color filter layers of red(R), green (G) and blue (B), in which three colors of R, G and B areassociated with each display pixel as a group. The touch detectionelectrodes TDL are formed on the other surface of the glass substrate31. The touch detection electrodes TDL are electrodes made of, forexample, ITO, having transparency. A polarizing plate 35 is arrangedover the touch detection electrodes TDL.

The liquid crystal layer 6 functions as a display function layer,modulating light transmitting through the layer in accordance with astate of an electric field. The electric field is formed by a potentialdifference between a voltage of the drive electrodes COML and a voltageof the pixel electrodes 22. Lateral-electric field mode liquid crystalsuch as FFS (fringe field switching) or IPS (in-plane switching) is usedfor the liquid crystal layer 6.

Alignment films are arranged between the liquid crystal layer 6 and thepixel substrate 2 and between the liquid crystal layer 6 and the countersubstrate 3, and further, an incident-side polarizing plate is arrangedon the lower surface side of the pixel substrate 2, which are not shownhere.

FIG. 7 shows a configuration example of a pixel structure in the liquidcrystal display device 20. The liquid crystal display device 20 hasplural pixels Pix arranged in matrix. Each pixel Pix includes threesub-pixels SPix. These sub-pixels SPix respectively correspond to threecolors (RGB) of the color filters 32 shown in FIG. 6. Each sub-pixelincludes a TFT device Tr and a liquid crystal device LC. The TFT deviceTr is formed by a thin film transistor, which is an n-channel MOS (MetalOxide Semiconductor) type TFT in this example. A source of the TFTdevice Tr is connected to a pixel signal line SGL, a gate is connectedto a scanning signal line GCL and a drain is connected to one terminalof the liquid crystal device LC. The liquid crystal device LC isconnected to the drain of the TFT device Tr at one terminal and isconnected to the drive electrode COML at the other terminal.

The sub-pixel SPix is connected to other sub-pixels SPix belonging tothe same row of the liquid crystal display device 20 to one another bythe scanning signal line GCL. The scanning signal line GCL is connectedto the gate driver 12 and the scanning signal Vscan is supplied from thegate driver 12. The sub-pixel SPix are also connected to othersub-pixels SPix belonging to the same column of the liquid crystaldisplay device 20 to one another by the pixel signal line SGL. The pixelsignal line SGL is connected to the selection switch unit 14 and thepixel signal Vpix is supplied from selection switch unit 14.

Moreover, the sub-pixel SPix is connected to other sub-pixels SPixbelonging to the same row of the liquid crystal display device 20 to oneanother by the drive electrode COML. The driver electrode COML isconnected to the drive electrode driver 16 and the drive signal Vcom (DCdrive signal VcomDC) is supplied from the drive electrode driver 16.

According to the above configuration, one horizontal line issequentially selected by driving the scanning signal lines GCL by thegate driver 12 so as to perform line-sequential scanning in the timedivision manner, and display is performed in units of horizontal linesby supplying the pixel signal Vpix to pixels Pix belonging to onehorizontal line by the source driver 13 and the selection switch unit 14in the liquid crystal display device 20.

FIG. 8 perspectively shows a configuration example of the touchdetection device 30. The touch detection device 30 includes the driveelectrodes COML provided in the pixel substrate 2 and the touchdetection electrodes TDL provided in the counter substrate 3. The driveelectrodes COML have a strip-shaped electrode pattern extending in aright and left direction of the drawing. When performing the touchdetection operation, the AC drive signal VcomAC is sequentially suppliedto respective electrodes in the pattern in units of blocks(later-described drive electrodes blocks B) each including the givennumber of drive electrodes COML and the scanning drive is sequentiallyperformed in the time division manner as described later. The touchdetection electrodes TDL have a strip-shaped electrode pattern extendingin a direction orthogonal to the extending direction of the electrodepattern of the drive electrodes COML. Respective electrodes in thepattern of the touch detection electrodes TDL are respectively connectedto inputs of the LPF unit 42 of the touch detection unit 40. In theelectrode patterns of the drive electrodes COML and the touch detectionelectrode TDL intersecting each other, capacitance is formed atintersections.

According to the above structure, the AC drive signal VcomAC applied tothe drive electrodes COML by the drive electrode driver 16 istransmitted to the touch detection electrodes TDL and outputted from thetouch detection electrodes TDL as the touch detection signal Vdet in thetouch detection device 30. That is, the drive electrodes COML correspondto the drive electrode E1 and the touch detection electrodes TDLcorrespond to the touch detection electrode E2 in the basic principlesof touch detection shown in FIGS. 1A to 3B. The touch detection device30 detects a touch in accordance with the basic principles. As shown inFIG. 8, the electrode patterns intersecting each other configure thecapacitance-type touch sensors in a matrix form. Therefore, scanning isperformed over the entire touch detection surface of the touch detectiondevice 30, thereby detecting a position where an external near-fieldobject touches or comes close to the sensor.

The drive electrode driver 16 performs the touch detection scanning bydriving the drive electrodes COML in units of blocks each including thegiven number of drive electrodes COML (drive electrode blocks B).

FIGS. 9A to 9C schematically show the touch detection scanning. In FIGS.9A to 9C, supply operation of the AC drive signal VcomAC to respectivedrive electrode blocks B1 to B20 in the case where the touch detectionsurface includes 20 pieces of drive electrode blocks B1 to B20 areshown. In FIGS. 9A to 9C, shaded drive electrode blocks B represent thatthe AC drive signal VcomAC is supplied, and other drive electrode blocksB represent that the DC drive signal VcomDC is supplied.

The drive electrode driver 16 applies the drive signal VcomAC to thedrive electrodes COML in units of the drive electrode blocks B. Eachdrive electrode block B is set to a width corresponding to, for example,the size of a user's finger (for example, approximately 5 mm). The driveelectrode driver 16 sequentially selects the drive electrode blocks B tobe targets of the touch detection operation and applies the AC drivesignal VcomAC to the drive electrodes COML belonging to the driveelectrode block B, thereby scanning the electrodes all over the driveelectrode blocks B. The number of the drive electrode blocks B is 20 inthe example for convenience of explanation, however, the presentdisclosure is not limited to the example.

[Operation and Effect]

Subsequently, operation and effect of the display panel 1 according tothe embodiment will be explained.

(Whole Operation Summary)

First, the whole operation summary of the display panel 1 will beexplained with reference to FIG. 4. The control unit 11 respectivelysupplies control signals to the gate driver 12, the source driver 13,the drive electrode driver 16 and the touch detection unit 40 based onthe video signal Vdisp and controls these units to operate insynchronization with one another. In the operation, the control unit 11controls these circuits so that the touch detection period Pt isprovided once every time the liquid crystal display device 20 of thedisplay device with the touch detection function 10 displays thehorizontal lines of two rows.

The gate driver 12 supplies the scanning signal Vscan to the liquidcrystal display device 20 and sequentially selects one horizontal lineto be a target of display driving. The source driver 13 generates thepixel signal Vsig obtained by multiplexing the pixel signals Vpix andthe corresponding switch control signals Vsel and supplies the signalsto the selection switch unit 14. The selection switch unit 14 separatesand generates the pixel signals Vpix based on the pixel signal Vsig andthe switch control signals Vsel, supplying the pixel signals Vpix torespective pixels Pix included in one horizontal line. The driveelectrode driver 16 applies the DC drive signal VcomDC to all the driveelectrodes COML in the display period Pd. The drive electrode driver 16also applies the AC drive signal VcomAC to the drive electrodes COMLbelonging to the drive electrode block B to be a target of the touchdetection operation as well as applies the DC drive signal VcomDC to thedrive electrodes COML other than the target. The display device with thetouch detection function 10 performs display operation in the displayperiod Pd as well as performs touch detection operation in the touchdetection period Pt, outputting the touch detection signal Vdet from thetouch detection electrodes TDL.

The touch detection unit 40 detects a touch on the touch detectionsurface based on the touch detection signal Vdet. Specifically, the LPFunit 42 removes high frequency components included in the touchdetection signal Vdet and takes out touch components to thereby outputthese components. The A/D converter 43 converts the analog signaloutputted from the LPF unit 42 into the digital signal. The signalprocessing unit 44 detects whether the touch detection surface has beentouched or not based on the output signal of the A/D converter 43. Thecoordinate extraction unit 45 calculates coordinates in the touch panelwhen the touch has been detected in the signal processing unit 44. Thedetection timing control unit 46 controls the LPF unit 42, the A/Dconverter 43, the signal processing unit 44 and the coordinateextraction unit 45 to operate in synchronization with one another.

(Detailed Operation)

Next, the operation of the display panel 1 will be explained in detailwith reference to some drawings.

FIGS. 10A to 10F show an example of timing waveforms of the displaypanel 1, in which FIG. 10A shows a waveform of the scanning signalVscan, FIG. 10B shows a waveform of the pixel signal Vsig, FIG. 10Cshows waveforms of the switch control signals Vsel, FIG. 10D showswaveforms of the pixel signal Vpix, FIG. 10E shows a waveform of thedrive signals Vcom and FIG. 10F shows a waveform of the touch detectionsignal Vdet.

In the display panel 1, the display operation and the touch detectionoperation are performed in each unit drive period PU which is providedrepeatedly. In the unit drive period PU, there are provided the touchdetection period Pt during which the touch detection operation isperformed and two display periods Pd1, Pd2 during which the displayoperation with respect to a horizontal line of one row is performedrespectively. In the display operation, the gate driver 12 sequentiallyapplies the scanning signal Vscan to the scanning signal lines GCL tothereby perform display scanning. In the touch detection operation, thedrive electrode driver 16 sequentially applies the AC drive signalVcomAC in units of the drive electrode blocks B to thereby perform thetouch detection scanning and the touch detection unit 40 detects a touchbased on the touch detection signal Vdet outputted from the touchdetection electrodes TDL. The details of the above will be explainedbelow.

First, the unit drive period PU starts and a touch detection period Ptstarts at a timing “t1”.

The drive electrode 16 applies the AC drive signal VcomAC to the driveelectrodes COML and the touch detection unit 40 performs touch detectionbased on the touch detection signal Vdet in a period from the timing“t1” to a timing “t2” (touch detection period Pt). Specifically, thedrive electrode driver 16 applies the AC drive signal VcomAC to thedrive electrodes COML included in the k-th drive electrode block B(k)relating to the touch detection operation in the touch detection periodPt (FIG. 10E). The AC drive signal VcomAC is transmitted to the touchdetection electrodes TDL through capacitance, and the touch detectionsignal Vdet is changed (FIG. 10F). Then, the touch detection unit 40performs touch detection based on the touch detection signal Vdet.

Next, the touch detection period Pt ends and the first display periodPd1 starts at the timing “t2”. In the display period Pd1, the displayoperation with respect to the n-th horizontal line is performed.

In the display period Pd1, the gate driver 12 applies the scanningsignal Vscan to the n-th scanning signal GCL(n) relating to the displayoperation at a timing “t3”, and the scanning signal Vscan(n) is changedfrom a low level to a high level (FIG. 10A). Accordingly, the gatedriver 12 selects the n-th horizontal line to be a target of the displayoperation.

Then, the source driver 13 supplies a pixel voltage VR for a redsub-pixel SPix to the selection switch unit 14 as the pixel signal Vsig(FIG. 10B) as well as generates the switch control signal VselR to be inthe high level in a period during which the pixel voltage VR is supplied(FIG. 10C). Then, the selection switch unit 14 turns on the switch SWRin the period during which the switch control signal VselR is in thehigh level, thereby separating the pixel voltage VR supplied from thesource driver 13 from the pixel signal Vsig and supplies the signal tothe red sub-pixel SPix through the pixel signal line SGL as the pixelsignal VpixR (FIG. 10D). As the pixel signal line SGL is in a floatingstate after the switch SWR is turned off, the voltage of the pixelsignal line SGL is maintained (FIG. 10D).

Similarly, the source driver 13 supplies a pixel voltage VG for thegreen sub-pixel SPix to the selection switch unit 14 with thecorresponding switch signal VselG (FIG. 10B), and the selection switchunit 14 separates the pixel voltage VG from the pixel signal Vsig basedon the switch control signal VselG and supplies the signal to the greensub-pixel SPix through the pixel signal line SGL as the pixel signalVpixG (FIG. 10D).

Subsequently, in a similar manner, the source driver 13 supplies a pixelvoltage VB for the blue sub-pixel SPix to the selection switch unit 14with the corresponding switch control signal VselB (FIGS. 10B and 10C),and the selection switch unit 14 separates the pixel voltage VB from thepixel signal Vsig based on the switch control signal VselB and suppliesthe signal to the blue sub-pixel SPix through the signal line SGL as thepixel signal VpixB (FIG. 10D).

Next, the gate driver 12 changes the scanning signal Vscan (n) of then-th scanning signal line GCL from the high level to the low level at atiming “t4” (FIG. 10A). Accordingly, the sub-pixels Spix in onehorizontal line relating to the display operation are electricallyseparated from the pixel signal lines SGL.

Then, the first display period Pd1 ends as well as the second displayperiod Pd2 starts at a timing “t5”. In the display period Pd2, thedisplay operation with respect to the (n+1)-th horizontal line isperformed in the same manner as the display period Pd1.

In the display period Pd2, the gate driver 12 applies the scanningsignal Vscan to the (n+1)-th scanning signal line GCL(n+1) relating tothe display operation at a timing “t6”, and the scanning signalVscan(n+1) is changed from a low level to a high level (FIG. 10A).Accordingly, the gate driver 12 selects the (n+1)-th horizontal line tobe a target of the display operation.

Then, the source driver 13 supplies the pixel voltage VR for the redsub-pixel Spix to the selection switch unit 14 with the correspondingswitch control signal VselR (FIG. 10B and 10C), and the selection switchunit 14 separates the pixel voltage VR from the pixel signal Vsig basedon the switch control signal VselR and supplies the signal to the redsub-pixel SPix through the pixel signal line SGL as the pixel signalVpixR (FIG. 10D). Similarly, the source driver 13 supplies the pixelsignal VpixG to the green sub-pixel SPix and supplies the pixel signalVpixB to the blue sub-pixel SPix (FIG. 10D).

Next, the gate driver 12 changes the scanning signal Vscan (n+1) of the(n+1)-th scanning signal line GCL from the high level to the low levelat a timing “t7” (FIG. 10A). Accordingly, the sub-pixels Spix in onehorizontal line relating to the display operation are electricallyseparated from the pixel signal lines SGL.

Then, the second display period Pd2 ends as well as the unit driveperiod PU ends at a timing “t8”, then, a new unit drive period PUsubsequently starts.

As the above operation is continuously repeated, the display operationin the entire display surface is performed by line-sequential scanningas well as the touch detection operation in the entire touch detectionsurface is performed by scanning the touch detection surface in units ofthe drive electrode blocks B as described below in the display panel 1.

(Touch Detection Operation)

Next, the touch detection operation will be explained in detail.

FIG. 11A shows a waveform of the AC drive signal VcomAC and FIG. 11Bshows a waveform of the touch detection signal Vdet. The AC drive signalVcomAC has two pulses. A pulse width and a pulse interval of these twopulses are set to time periods tw which are equivalent to each other.The time period tw is, for example, 2 [usec]. When the AC drive signalVcomAC is transmitted to the touch detection electrodes TDL throughcapacitance, the touch detection signal Vdet shown in FIG. 11B isgenerated.

The A/D converter 43 of the touch detection unit 40 performs A/Dconversion of the output signal of the LPF unit 42 to which the touchdetection signal Vdet is inputted at timings before and after respectivetransitions of the AC drive signal VcomAC (sampling timings ts1 to ts8)(FIG. 11B) to calculate data D (ts1) to Data D(ts8).

Then, the signal processing unit 44 of the touch detection unit 40calculates variations R1 (=D(ts2)−D(ts1)), F1 (=D(ts4)−D(ts3)), R2(=D(ts6)−D(ts5)) and F2 (=D(ts8)−D(ts7)) of the touch detection signalVdet in respective transitions based on these data D(ts1) to D(ts8).That is, variations R1 and R2 have positive values (R1, R2>0) andvariations F1 and F2 have negative values (F1, F2<0).

Next, the signal processing unit 44 calculates detection data DD in thetouch detection period Pt by using the following expression based onthese variations R1, F1, R2 and F2.

DD=R1−F1+R2−F2  (1)

The signal processing unit 44 collects the detection data DD in pluralunit drive periods PU (plural touch detection periods Pt) and performstouch detection based on the detection data DD as explained below.

FIGS. 12A and 12B show an operation example of touch detection scanning,in which FIG. 12A shows a waveform of the drive signal Vcom and FIG. 12Bshows a waveform of the touch detection signal Vdet.

The drive electrode driver 16 performs touch detection scanning bysequentially applying the AC drive signal VcomAC to the drive electrodesCOML in units of the drive electrode blocks B as shown in FIGS. 12A and12B. In the operation, the drive electrode driver 16 applies the ACdrive signal VcomAC with respect to respective drive electrode blocks Bover the given plural (for example, 30 pieces) unit drive periods PU(FIG. 12A). The touch detection unit 40 samples the touch detectionsignal Vdet based on the AC drive signal VcomAC and calculates thedetection data DD in each unit drive period PU. Then, the signalprocessing unit 44 averages 30 pieces of detection data DD, for example,by a FIR (Finite Impulse Response) filter with 30 taps to detect whetheran area corresponding to the drive electrode block B has been touched ornot. As the touch detection is performed based on plural samplingresults as described above, the sampling results can be statisticallyanalyzed, which can suppress reduction of the S/N ratio due tovariations in sampling results and can increase the accuracy of touchdetection.

(Prevention of Malfunction in Touch Detection Operation)

There is a danger that noise (disturbance noise) due to an inverterfluorescent lamp, AM radio waves, an AC power supply and so onpropagates through the touch panel to cause malfunction in thecapacitance-type touch panel. The malfunction is due to the fact that itis difficult to distinguish between the signal relating tocontact/non-contact (touch signal) and the disturbance noise. It ispossible to suppress the malfunction in the display panel 1 as the ACdrive signal VcomAC includes two pulses. The details will be explainedbelow.

FIGS. 13A to 13D schematically show sampling operations when disturbancenoise is applied, in which FIG. 13A shows a waveform of the AC drivesignal VcomAC and FIG. 13B to 13D respectively show examples of noisesignals to be superimposed on the touch detection signal Vdet due to thedisturbance noise.

First, a case of a noise signal VN1 shown in FIG. 13B will be explained.The noise signal VN1 is a signal with a cycle of the time period “tw”,and a frequency thereof is 500 [kHz] when the time period “tw” is 2[usec].

As shown in FIG. 13B, the noise signal VN1 changes with the samevariation (noise n1) before and after respective transitions of the ACdrive signal VcomAC. Therefore, when the noise signal VN1 issuperimposed on the touch detection signal Vdet, the detection data DDis represented by the following expression.

$\begin{matrix}{{DD} = {{\left( {{R\; 1} + {n\; 1}} \right) - \left( {{F\; 1} + {n\; 1}} \right) + \left( {{R\; 2} + {n\; 1}} \right) - \left( {{F\; 2} + {n\; 1}} \right)} = {{R\; 1} - {F\; 1} + {R\; 2} - {F\; 2}}}} & (2)\end{matrix}$

That is, for example, the noise n1 relating to a rising edge of thefirst pulse of the AC drive signal VcomAC and the noise n1 relating to afalling edge cancel each other out, and the noise n1 relating to therising edge of the second pulse of the AC drive signal VcomAC and thenoise n1 relating to the falling edge cancel each other out, therefore,the noise n1 does not appear in the detection data DD as shown in theexpression (2). In other words, as the noises n1 (a pair P1) having thesame polarity are generated at a transition timing pair PA havingreverse polarities in the AC drive signal VcomAC in the noise signalVN1, the noises cancel each other out. Therefore, the noise signal VN1does not affect the touch detection operation.

In the noise signals having integral multiple frequencies of the noisesignal VN1, noises are also cancelled out due to the same principles,which do not affect the touch detection operation.

Next, a case of a noise signal VN2 shown in FIG. 13C will be explained.The noise signal VN2 is a signal with a cycle of 4/3 times of the timeperiod “tw”, and a frequency thereof is 375 [kHz] when the time period“tw” is 2 [usec].

As shown in FIG. 13C, the noise signal VN2 changes with a variation of anoise n2 before and after the rising edge of the first pulse of the ACdrive signal VcomAC and changes with a variation of a noise (−n2) beforeand after the rising edge of the second pulse. Therefore, when the noisesignal VN2 is superimposed on the touch detection signal Vdet, thedetection data DD is represented by the following expression.

$\begin{matrix}{{DD} = {{\left( {{R\; 1} + {n\; 2}} \right) - {F\; 1} + \left( {{R\; 2} - {n\; 2}} \right) - {F\; 2}} = {{R\; 1} - {F\; 1} + {R\; 2} - {F\; 2}}}} & (3)\end{matrix}$

That is, as the noise n2 relating to the rising edge of the first pulseof the AC drive signal VcomAC and the noise (−n2) relating to the risingedge of the second pulse of the AC drive signal VcomAC cancel each otherout in this example, the noise n2 does not appear in the detection dataDD as shown in the expression (3). In other words, as the noises n2 and−n2 (a pair P2) having reverse polarities are generated at a transitiontiming pair PB having the same polarity in the AC drive signal VcomAC inthe noise signal VN2, the noises cancel each other out. Therefore, thenoise signal VN2 does not affect the touch detection operation.

Next, a case of a noise signal VN3 shown in FIG. 13D will be explained.The noise signal VN3 is a signal with a cycle of 4 times of the timeperiod “tw”, and a frequency thereof is 125 [kHz] when the time period“tw” is 2 [usec].

As shown in FIG. 13D, the noise signal VN3 changes with a variation of anoise n3 before and after the rising edge of the first pulse of the ACdrive signal VcomAC and changes with a variation of a noise (−n3) beforeand after the rising edge of the second pulse. Therefore, when the noisesignal VN3 is superimposed on the touch detection signal Vdet, thedetection data DD is represented by the following expression.

$\begin{matrix}{{DD} = {{\left( {{R\; 1} + {n\; 3}} \right) - {F\; 1} + \left( {{R\; 2} - {n\; 3}} \right) - {F\; 2}} = {{R\; 1} - {F\; 1} + {R\; 2} - {F\; 2}}}} & (4)\end{matrix}$

That is, as the noise n3 relating to the rising edge of the first pulseof the AC drive signal VcomAC and the noise (−n3) relating to the risingedge of the second pulse of the AC drive signal VcomAC cancel each otherout in this example, the noise n3 does not appear in the detection dataDD as shown in the expression (4). In other words, as the noises n3 and−n3 (a pair P3) having reverse polarities are generated at thetransition timing pair PB having the same polarity in the AC drivesignal VcomAC in the noise signal VN3 in the same manner as the case ofthe noise signal VN2, the noises cancel each other out. Therefore, thenoise signal VN3 does not affect the touch detection operation.

The frequency of the noise signal VN2 is 3 times of the frequency of thenoise signal VN3, and noises are cancelled out in the noise signals VN2and VN3 due to the same principles as described above. Accordingly, inthe noise signals having odd-number multiple frequencies of the noisesignal VN3, noises are cancelled out due to the same principles, whichdo not affect the touch detection operation.

As explained above, the display panel 1 can cancel out noises in noisesignals having various frequencies such as the noise signals VN1 to VN3.These frequencies can be changed by adjusting, for example, the timeperiod “tw”. Accordingly, in the display panel 1, the pulse width andthe pulse interval of the AC drive signal VcomAC are adjusted so as tocancel out noises in the case where the frequency of disturbance noiseis known, thereby improving resistance with respect to the disturbancenoise.

As described above, the AC drive signal includes plural pulses in thedisplay panel 1, therefore, resistance with respect to noises havingplural frequencies (125 [kHz], 375 [kHz], 500 [kHz] and so on in theexample) can be increased. Accordingly, the resistance with respect todisturbance noise can be improved not only in the case where disturbancenoise of single frequency is applied but also in the case where, forexample, disturbance noise of plural frequencies or disturbance noisewith a wider spectrum is applied in the display panel 1.

In the display panel 1, one touch detection period Pt is provided ineach display operation of two rows. That is, two touch detection periodsin the case where the touch detection period is provided in each displayoperation of one row are integrated into one period in the display panel1, thereby obtaining one touch detection period Pt having a longer timewidth. In the display panel 1, the resistance with respect to noise isincreased by effectively using the longer touch detection period Ptobtained in the above manner. Namely, in the display panel 1, the touchdetection operation is performed by using the AC drive signal VcomAChaving plural pulses in the touch detection period Pt, therebycancelling out noises of plural frequencies as described above, whichcan increase the resistance with respect to noise.

As described above, the touch detection period Pt is provided in eachdisplay operation of two rows in the display panel 1, therefore, a largeunit of time for the touch detection operation can be secured and thusthe degree of freedom in the touch detection operation can be improved.

[Effects]

As the touch detection period is provided in each display operation ofplural rows in the embodiment as described above, the longer touchdetection period can be obtained and the degree of freedom in the touchdetection operation can be increased. Specifically, for example, thenumber of pulses of the AC drive signal to be applied during the touchdetection period can be increased or the pulse width or a pulse positioncan be changed.

In particular, in the case where the AC drive signal includes pluralpulses in the touch detection period secured as described above in theembodiment, noises in plural noise signals having frequencies differentfrom one another can be cancelled out and the danger of malfunction dueto noise can be reduced.

Modification Example 1-1

The one touch detection period Pt is provided in each display operationof two rows in the above embodiment, however, the present disclosure isnot limited to the above, and any other configurations can be applied aslong as the touch detection periods Pt which are lower in number thanthe number of rows are provided in each display operation of a pluralnumber of rows. Specifically, for example, it is possible to provide onetouch detection period Pt in each display operation of four rows asshown in FIGS. 14A and 14B. As the time width of the touch detectionperiod Pt can be longer than the case of the embodiment (FIGS. 10A to10F) in this case, the degree of freedom in the touch detectionoperation can be increased, such that the AC drive signal VcomACincludes much more pulses (four pulses in this example). Additionally,for example, three touch detection periods Pt may be provided in eachdisplay operation of four rows as shown in FIGS. 15A and 15B. In theexample, the touch detection periods Pt1 to Pt3 and the display periodsPd1 to Pd4 are arranged in the order of Pt1, Pd1, Pt2, Pd2, Pt3, Pd3 andPd4. As described above, as the touch detection periods Pt which arelower in number than the number of rows are provided in each displayoperation of a plural number of rows, thereby allowing the touchdetection period to be longer and increasing the degree of freedom inthe touch detection operation.

Modification Example 1-2

The AC drive signal VcomAC includes two pulses in the above embodiment,however, the present disclosure is not limited to the above, and it ispossible to the AC drive signal VcomAC includes, for example, three ormore pulses instead of the above. According to the configuration, muchmore noise components can be cancelled out and the resistance withrespect to disturbance noise can be improved.

Modification Example 1-3

The pulse widths and the pulse intervals of the AC drive signal VcomACare equal to one another in the above embodiment, however, the presentdisclosure is not limited to the above, and it is possible to allow thepulse widths and the pulse intervals of respective pulses to bedifferent from one another instead of the above.

Modification Example 1-4

In addition to the above configurations of the embodiments, it is alsopreferable to set the time width of the unit drive period PU to bevariable. Accordingly, the resistance with respect to disturbance noisein the vicinity of an integral multiple frequency corresponding to areciprocal of the time period of the unit drive period PU can be furtherincreased. Hereinafter, the details of the display panel according tothe present modification example will be explained.

FIGS. 16A to 16D represent timing charts of an operation in the casewhere the time width of the unit drive period PU is short and FIGS. 16Eto 16H represent timing charts of an operation in the case where thetime width of the unit drive period PU is long. In FIGS. 16A to 16H,FIGS. 16A and 16E represent waveforms of the scanning signals Vscan,FIGS. 16B and 16F represent waveforms of the pixel signals Vsig, FIGS.16C and 16G represent waveforms of the switch control signals Vsel andFIGS. 16D and 16H represent waveforms of the drive signals Vcom.

In the display panel according to the present modification example, thetime width of the unit drive period PU can be changed as shown in FIGS.16A to 16H. Specifically, the time width of the unit drive period PU ischanged by changing a time period after the scanning signal Vscan ischanged from the high level to the low level in respective displayperiods Pd1 and Pd2. Accordingly, the danger of malfunction in the touchdetection operation due to disturbance noise can be reduced.

When the disturbance noise is A/D converted in the A/D converser 43 inthe case where the frequency of disturbance noise is in the vicinity ofthe integral multiple frequency corresponding to a reciprocal of thetime period of the unit drive period PU, the disturbance noise appearsin the vicinity of a frequency “0” as a so-called folding noise. As aresult, the folding noise is mixed with a touch signal in the vicinityof the frequency “0”, it is difficult to distinguish between the touchsignal and the noise signal. As the time width of the unit drive periodPU can be changed in the display panel according to the presentmodification example, the touch detection can be performed by selectingconditions in which the touch detection is not affected by disturbancenoise.

Modification Example 1-5

The unit drive period PU includes the display period Pd1 and Pd2relating to the n-th row and the (n+1)th row in the above embodiment,and it is possible to change the configuration according to frames. Thedetails will be explained below.

FIGS. 17A and 17B represent timing charts of an operation in a certainframe period Pf1 and FIGS. 17C and 17D represent timing charts of anoperation in another certain frame period Pf2. In FIGS. 17A to 17D,FIGS. 17A and 17C represent waveforms of the scanning signals Vscan andFIGS. 17B and 17D represent waveforms of the drive signals Vcom. In thedisplay panel according to the present modification example, the frameperiod Pf1 and the frame period Pf2 are alternately arranged.

As shown in FIGS. 17A to 17D, display periods relating to the n-th rowand the (n+1)th row form the unit drive period PU in the frame periodPf1, and display periods relating to the (n+1)th row and the (n+2)th rowform the unit drive period PU in the frame period Pf2. In other words,for example, the display operation of the (n+1)th row is performed inthe second display period Pd2 in the unit drive period PU in the frameperiod Pf1 (FIGS. 17A and 17B), and the display operation of the (n+1)throw is performed in the first display period Pd1 in the unit driveperiod PU in the frame period Pf2 (FIGS. 17C and 17D).

The present modification example is effective, for example, when thetouch detection operation in the touch detection period Pt affects thedisplay operation in the display period Pd1 just after the touchdetection period Pt. That is, for example, the display operation of the(n+1)th row is performed in the display period Pd1 in the frame periodPf2 as shown in FIGS. 17C and 17D in this case, therefore, the displayoperation is affected by the touch detection operation in the touchdetection period Pt existing before the display period Pd1, however, thedisplay operation of the (n+1)th row is performed in the display periodPd2 in the frame period Pf1 as shown in FIGS. 17A and 17B, therefore,the display operation is not affected by the touch detection operation.Similarly, display operations of other rows are affected by the touchdetection operation only in one of the frame periods Pf1 and Pf2.Accordingly, as display operations, for example, in particular rows arenot affected by the touch detection operation in the display panelaccording to the present modification example, the reduction in imagequality can be suppressed.

3. Second Embodiment

Next, a display panel 5 according to a second embodiment will beexplained. The embodiment is configured so that the pulse width of theAC drive signal VcomAC can be changed by using the high degree offreedom in the touch detection operation obtained by securing a longertouch detection period. That is, the AC drive signal includes pluralpulses to thereby increase the resistance with respect to plural noiseshaving frequencies different from one another in the first embodiment(FIGS. 11A and 11B). In the present embodiment, the same effect can beobtained by changing the pulse width instead of the above. Componentssubstantially the same as the display panel 1 according to the firstembodiment are denoted by the same symbols and the explanation will beappropriately omitted.

The display panel 5 includes a drive electrode driver 56 (FIG. 4). Thedrive electrode driver 56 generates an AC drive signal VcomAC includingone pulse. In the operation, the drive electrode driver 56 can changethe pulse width of the pulse.

FIGS. 18A and 18B represent waveforms of the AC drive signal VcomAC andthe touch detection signal Vdet in the case where the pulse width isnarrowed (case C1), and FIGS. 18C and 18D represent waveforms of the ACdrive signal VcomAC and the touch detection signal Vdet in the casewhere the pulse width is widened (case C2). A pulse width “tw2” (FIG.18A) in the case C1 is, for example, 4 [usec] and a pulse width “tw3”(FIG. 18C) in the case C2 is, for example, 6 [usec]. These AC drivesignals VcomAC (FIGS. 18A and 18C) are transmitted to the touchdetection electrodes TDL through capacitance in the same manner as thecase of the first embodiment, thereby generating the touch detectionsignals Vdet shown in FIGS. 18B and 18D.

The A/D converter 43 of the touch detection unit 40 performs A/Dconversion of the output signal of the LPF unit 42 to which the touchdetection signal Vdet is inputted at timings before and after respectivetransitions in the AC drive signal VcomAC (sampling timings ts1 to ts4)(FIGS. 18B and 18D) to calculate data D (ts1) to Data D(ts4).

Then, the signal processing unit 44 of the touch detection unit 40calculates variations R1 (=D(ts2)−D(ts1)) and F1 (=D(ts4)−D(ts3)) of thetouch detection signal Vdet in respective transitions based on thesedata D(ts1) to D(ts4). That is, a variation R1 has a positive values(R1>0) and a variation F1 has a negative value (F1<0).

Next, the signal processing unit 44 calculates a detection data DD inthe touch detection period Pt by using the following expression based onthese variations R1 and F1.

DD=R1−F1  (5)

Then, the signal processing unit 44 performs touch detection based onthe detection data DD collected in plural unit drive period PU in thesame manner as the case of the first embodiment.

Subsequently, operations performed when disturbance noise is appliedwill be explained concerning the case where the pulse width is narrowed(case C1) and the case where the pulse width is widened (case C2)respectively in this order.

FIGS. 19A to 19C schematically show sampling operations performed whenthe pulse width is narrowed (case C1), in which FIG. 19A shows awaveform of the AC drive signal VcomAC and FIG. 19B and 19C respectivelyshow examples of noise signals to be superimposed on the touch detectionsignal Vdet.

The noise signal VN4 (FIG. 19B) is a signal with a cycle of the half ofthe time period “tw2”, and a frequency thereof is 500 [kHz] when thetime period “tw2” is 4 [usec]. As shown in FIG. 19B, the noise signalVN4 changes with the same variation (noise n4) at respective transitionsof the AC drive signal VcomAC. Therefore, when the noise signal VN4 issuperimposed on the touch detection signal Vdet, the detection data DDis represented by the following expression.

$\begin{matrix}{{DD} = {{\left( {{R\; 1} + {n\; 4}} \right) - \left( {{F\; 1} + {n\; 4}} \right)} = {{R\; 1} - {F\; 1}}}} & (6)\end{matrix}$

That is, for example, the noise n4 relating to the rising edge of the ACdrive signal VcomAC and the noise n4 relating to the falling edge canceleach other out, therefore, the noise n4 does not appear in the detectiondata DD as shown in the expression (6).

The noise signal VN5 (FIG. 19C) is a signal with a cycle of the timeperiod “tw2”, and a frequency thereof is 250 [kHz] when the time period“tw2” is 4 [usec]. As shown in FIG. 19C, the noise signal VN5 changeswith the same variation (noise n5) at respective transitions of the ACdrive signal VcomAC. Therefore, the noise n5 does not appear in thedetection data DD in the same manner as the case of the noise signalVN4.

As described above, the noises having the same polarity are generated ata transition timing pair PC having reverse polarities in the AC drivesignal VcomAC in the noise signals VN4 and VN5, therefore, the noisescancel each other out. Similarly, in the noise signals having integralmultiple frequencies of the noise signal VNS, noises are also cancelledout due to the same principles, which do not affect the touch detectionoperation.

FIGS. 20A to 20D schematically show sampling operations performed whenthe pulse width is widened (case C2), in which FIG. 20A shows a waveformof the AC drive signal VcomAC and FIGS. 20B and 20D respectively showexamples of noise signals to be superimposed on the touch detectionsignal Vdet.

The noise signal VN6 (FIG. 20B) is a signal with a cycle of ⅓ of thetime period “tw3”, and a frequency thereof is 500 [kHz] when the timeperiod “tw3” is 6 [usec]. As shown in FIG. 20B, the noise signal VN6changes with the same variation (noise n6) at respective transitions ofthe AC drive signal VcomAC. Therefore, when the noise signal VN6 issuperimposed on the touch detection signal Vdet, the detection data DDis represented by the following expression.

$\begin{matrix}{{DD} = {{\left( {{R\; 1} + {n\; 6}} \right) - \left( {{F\; 1} + {n\; 6}} \right)} = {{R\; 1} - {F\; 1}}}} & (7)\end{matrix}$

That is, for example, the noise n6 relating to the rising edge of the ACdrive signal VcomAC and the noise n6 relating to the falling edge canceleach other out, therefore, the noise n6 does not appear in the detectiondata DD as shown in the expression (7).

The noise signal VN7 (FIG. 20C) is a signal with a cycle of the half ofthe time period “tw3”, and a frequency thereof is 333 [kHz] when thetime period “tw3” is 6 [usec]. As shown in FIG. 20C, the noise signalVN7 changes with the same variation (noise n7) at respective transitionsof the AC drive signal VcomAC. Therefore, the noise n7 does not appearin the detection data DD in the same manner as the case of the noisesignal VN6.

The noise signal VN8 (FIG. 20D) is a signal with a cycle of the timeperiod “tw3”, and a frequency thereof is 166 [kHz] when the time period“tw3” is 6 [usec]. As shown in FIG. 20D, the noise signal VN8 changeswith the same variation (noise n8) at respective transitions of the ACdrive signal VcomAC. Therefore, the noise n8 does not appear in thedetection data DD in the same manner as the case of the noise signalVN6.

As described above, the noises having the same polarity are generated ata transition timing pair PD having reverse polarities in the AC drivesignal VcomAC in the noise signals VN6 to VN8, therefore, the noisescancel each other out. Similarly, in the noise signals having integralmultiple frequencies of the noise signal VN8, noises are also cancelledout due to the same principles, which do not affect the touch detectionoperation.

As described above, in the display panel 5, noises such as 250 [kHz],500 [kHz] and so on can be cancelled out in the example when the pulsewidth is narrowed (case C1) and noises such as 166 [kHz], 333 [kHz], 500[kHz] and so on can be cancelled out when the pulse width is widened(case C2). Consequently, it is possible to increase the resistance withrespect to noises with various frequencies by changing the pulse widthin the display panel 5.

Specifically, for example, it is preferable that, after a condition(pulse width) in which effects of noises are reduced by changing thepulse width is calculated, the touch detection operation is performed inthe condition, or for example, it is also preferable that the touchdetection is performed while changing the pulse width in each givenperiod (for example, one frame period), and only detection results inconditions with many noises are thrown away. Furthermore, it ispreferable that the touch detection operation is normally performed witha given pulse width, and the touch detection operation is continued bychanging the pulse width when noise is observed. As methods of measuringnoise, for example, a method of using detection data on the wholesurface of the touch detection surface obtained by the touch detectionoperation or a method of providing a dedicated frame for measuring noisecan be considered.

As described above, the pulse width of the AC drive signal is changed inthe longer touch detection period in which the touch detection period isprovided in each display operation of plural rows in the presentembodiment, therefore, noises in plural noise signals having frequenciesdifferent from one another can be cancelled out and the danger ofmalfunction due to noise can be reduced.

Modification Example 2-1

The pulse width is switched between two pulse widths “tw2” and “tw3”(cases C1 and C2) in the above embodiment, however, the presentdisclosure is not limited to the above and the pulse width may beswitched between three or more pulse widths instead of the above.

Modification Example 2-2

The modification examples 1-1, 1-4 and 1-5 of the first embodiment canbe applied in the above embodiment.

Modification Example 2-3

In the above embodiment, the detection data DD obtained by using the ACdrive signal VcomAC having the same pulse width is averaged by the FIRfilter to thereby perform touch detection, however, the presentdisclosure is not limited to the above. It is also preferable that thedetection data DD obtained by using the AC drive signal VcomAC havingpulse widths different from one another while switching the pulse widthin units of unit detection periods PU is averaged by the FIR filter toperform touch detection.

4. Third Embodiment

Next, a display panel 6 according to a third embodiment will beexplained. The embodiment is configured so that the number of pulses ofthe AC drive signal VcomAC is increased in the same manner as the firstembodiment as well as the pulse width and the pulse interval can bechanged by using the high degree of freedom in the touch detectionoperation obtained by securing the longer touch detection period.Components substantially the same as the display panels 1 and 2according to the first and second embodiments are denoted by the samesymbols and the explanation will be appropriately omitted.

The display panel 6 includes a drive electrode driver 66 (FIG. 4). Thedrive electrode driver 66 generates the AC drive signal VcomAC includingplural pulses. In the operation, the drive electrode driver 66 canchange the pulse width and the pulse interval.

FIGS. 22A and 22B represent examples of waveforms of the AC drive signalVcomAC and the touch detection signal Vdet, FIGS. 22C and 22D representwaveforms of the AC drive signal VcomAC and the touch detection signalVdet obtained when the pulse width is narrowed while maintaining a pulsecycle and FIGS. 22E and 22F represent waveforms of the AC drive signalVcomAC and the touch detection signal Vdet obtained when the pulseinterval is narrowed while maintaining the pulse width.

The A/D converter 43 of the touch detection unit 40 performs A/Dconversion of the output signal of the LPF unit 42 to which the touchdetection signal Vdet is inputted at timings before and after respectivetransitions in the AC drive signal VcomAC (sampling timings ts1 to ts8)(FIGS. 22B, 22D and 22F) to calculate data D (ts1) to Data D (ts8) inthe same manner as the first embodiment. Then, the signal processingunit 44 of the touch detection unit 40 calculates detection data DDbased on the data D(ts1) to D(ts8), and performs touch detection basedon the detection data DD.

In the display panel 6, the touch detection is performed in conditionswith reduced noise by changing the pulse width or the pulse interval inthe same manner as in the case of the display panel 5 according to thesecond embodiment, thereby increasing the resistance with respect tonoises of various frequencies.

As described above, the AC drive signal includes plural pulses as wellas the pulse width and the pulse interval are changed in the longertouch detection period in which the touch detection period is providedin each display operation of plural rows, therefore, the danger ofmalfunction due to noise can be reduced. Other effects are the same asthe cases of the first and second embodiments.

Modification Example 3-1

The modification examples 1-1, 1-2, 1-4 and 1-5 of the first embodimentcan be applied in the above embodiment.

Modification Example 3-2

Also in the above embodiment, it is possible to perform touch detectionoperation while switching the pulse width, for example, in each unitdrive period PU in the same manner as the modification example 2-3 ofthe second embodiment.

5. Fourth Embodiment

Next, a display panel 7 according to a forth embodiment will beexplained. The embodiment is configured so that a pulse position of theAC drive signal VcomAC can be changed by using the high degree offreedom in the touch detection operation obtained by securing a longertouch detection period. Components substantially the same as the displaypanels 1, 5 and 6 according to the first to third embodiments aredenoted by the same symbols and the explanation will be appropriatelyomitted.

The display panel 7 includes a drive electrode driver 76 (FIG. 4). Thedrive electrode driver 76 generates the AC drive signal VcomAC includingone pulse. In the operation, the drive electrode driver 76 can changethe pulse position.

FIGS. 23A and 23B represent timing waveform examples of the displaypanel 7, in which FIG. 23A represents waveforms of the scanning signalsVscan and FIG. 23B represents the drive signal Vcom.

As shown in FIGS. 23A and 23B, the drive electrode driver 76 generatesthe AC drive signal Vcom in which pulse positions are different from oneanother in respective touch detection periods Pt. Accordingly, pulseintervals (T1, T2) of the AC drive signal Vcom can be changed in thedisplay panel 7, which can reduce the danger of malfunction in the touchdetection operation due to disturbance noise in the same manner as themodification example 1-4 of the first embodiment (FIGS. 16A to 16H).

As described above, the pulse position of the AC drive signal is changedin each the longer touch detection period in which the touch detectionperiod is provided in each display operation of plural rows in thepresent embodiment, which can reduce the danger of malfunction due tonoise.

Modification Example 4-1

The modification examples 1-1 and 1-5 of the first embodiment can beapplied in the above embodiment.

6. Fifth Embodiment

Next, a display panel 8 according to a fifth embodiment will beexplained. A high-definition liquid crystal display device is used inthe present embodiment. Components substantially the same as the displaypanel 1 according to to the first embodiment are denoted by the samesymbols and the explanation will be appropriately omitted.

The display panel 8 includes a display device with a touch detectionfunction 80 having a liquid crystal display device 81 (FIG. 4). Theliquid crystal display device 81 can perform display, for example, HD(High Definition) video, which has a resolution of, for example, 1920pixels×1080 pixels.

FIGS. 24A to 24F represent timing waveform examples of the display panel8, in which FIG. 24A represents waveforms the scanning signals Vscan,FIG. 24B represent a waveform of the pixel signal Vsig, FIG. 24Crepresent waveforms of the switch control signals Vsel, FIG. 24Drepresent waveforms of the pixel signals Vpix, FIG. 24E representwaveforms of the drive signal Vcom and FIG. 24F represent a waveform ofthe touch detection signal Vdet.

In the display panel 8, the touch detection operation (touch detectionperiod Pt) and the display operation of two rows (display periods Pd1and Pd2) are performed in each unit drive period PU in the same manneras the display panel 1 and the like according to the first embodiment.In the example, the AC drive signal VcomAC includes one pulse. As theresolution of the liquid crystal display device 81 is high in thedisplay panel 8, the time width of the unit drive period PU is shorterthan the display panel 1 according to the first embodiment (FIGS. 10A to10F).

It is difficult to perform touch detection operation in thehigh-resolution display panel. That is, it is necessary to performdisplay operation of many horizontal lines in one frame period (forexample, 16.6 [msec]= 1/60 [Hz]) when the resolution is high, time to beassigned to the touch detection operation is reduced.

In the display panel 8, one touch detection period Pt is provided ineach display operation of two rows as shown in FIGS. 24A to 24F, therebysecuring a longer period of time for the touch detection operation.Accordingly, the touch detection operation can be performed by using theAC drive signal VcomAC by effectively using the touch detection periodPt secured in the above manner in the display panel 8.

As described above, the touch detection period is provided in eachdisplay operation of plural rows in the present embodiment, therefore, asufficient period of time for performing the touch detection operationcan be secured even when the resolution of the display panel is high.

Modification Example 5-1

One touch detection period Pt is provided in each display operation oftwo rows in the above embodiment, however, the present disclosure is notlimited to this, and any other configurations can be applied as long asthe touch detection periods Pt which are lower in number than the numberof rows are provided in each display operation of a plural number ofrows. Accordingly, it is possible to set the touch detection period tobe longer, therefore, the touch detection operation can be performedeven when the resolution of the display panel is high.

Modification Example 5-2

The AC drive signal VcomAC includes one pulse in the above embodiment,however, the present disclosure is not limited to the above, and it isalso preferable that the AC drive signal VcomAC includes plural pulsesin the same manner as the first embodiment and so on. It is alsopreferable that the display panel is configured so that the pulse widthof the AC drive signal VcomAC can be changed. Accordingly, noisecomponents of various frequencies can be cancelled out and theresistance with respect to these disturbance noises can be increased. Itis further preferable to apply respective modification examples of thefirst and second embodiments.

7. Application Examples

Next, application examples of the display panel explained in the aboveembodiments and the modification examples will be explained.

FIG. 25 shows an appearance of a television apparatus to which thedisplay panel according to the above embodiments and the like isapplied. The television apparatus has, for example, a video displayscreen unit 510 including a front panel 511 and a filter glass 512, inwhich the video display screen unit 510 is configured by using thedisplay panel according to the above embodiments and so on.

The display panel according to the above embodiments and so on can beapplied to electronic apparatuses in various fields, which are, forexample, a digital camera, a notebook personal computer, portableterminal devices such as a cellular phone, portable game machines, avideo camera and so on, in addition to the television apparatus. Inother words, the display panel according to the above embodiments and soon can be applied to electronic apparatuses in various fields whichdisplay video.

The technology of the present disclosure has been explained as the aboveby citing some embodiments, modification examples and applicationexamples to the electronic apparatus, and the technology of the presentdisclosure is not limited to the above embodiments and so on and variousmodifications can be made.

For example, the selection switch unit 14 is provided and the pixelsignals Vpix are separated from the pixel signal Vsig supplied from thesource driver 13 and supplied to the liquid crystal display device 20 inthe respective embodiments, however, the present disclosure are notlimited to this, and it is also preferable that the selection switchunit 14 is not provided and that the source driver 13 directly suppliesthe pixel signals Vpix to the liquid crystal display device 20.

For example, the drive electrode driver 16 applies the DC drive signalVcomDC to the drive electrodes COML at the time of the display operationin the respective embodiments, however, the present disclosure is notlimited to the above, and for example, a so-called COM inverse drive inwhich the AC drive signal is applied to the drive electrodes COML may beperformed instead of the above.

Furthermore, for example, the drive electrodes COML are driven andscanned in units of drive electrode blocks B each having the givennumber of drive electrodes COML at the time of the touch detectionoperation in the above respective embodiments and so on, however, thepresent disclosure is not limited to the above. It is also possible tosimultaneously drive the given number of drive electrodes COML as wellas to scan the drive electrodes COML to be scanned by shifting theelectrodes one by one instead of the above. The details thereof will beexplained below.

FIGS. 26A to 26C schematically show an example of a touch detectionoperation according to the modification example. A drive electrodedriver according to the modification example applies the AC drive signalVcomAC to the given number of drive electrodes COML at the same time.Specifically, the drive electrode driver applies the AC drive signalVcomAC to the given number (5 in the example) of drive electrodes COMLat the same time (shaded portions) and performs touch detection scanningby shifting the drive electrodes COML to which the AC drive signalVcomAC is applied one by one. The AC drive signal VcomAC is applied tofive drive electrodes COML at the same time in the example, however, thepresent disclosure is not limited to this, and it is also preferable toapply the AC drive signal VcomAC simultaneously to the drive electrodesCOML of four or less as well as 6 or more instead of the above. Thedrive electrodes COML to which the AC drive signal VcomAC is applied areshifted one by one in the example, however, the present disclosure isnot limited to this. It is also possible to shift the drive electrodesCOML in units of two or more electrodes.

Additionally, the AC drive signal VcomAC includes positive-voltagepulses based on the DC drive signal VcomDC, for example, shown in FIG.11A, however, the present disclosure is not limited to the above, andthe AC drive signal VcomAC may include negative-voltage pulses insteadof the above. It is also preferable that the AC drive signal VcomACincludes both the positive-voltage pulse and the negative-voltage pulseas shown, for example, in FIG. 27A and FIG. 28A. The AD drive signalVcomAC shown in FIG. 27A includes a positive-voltage pulse in the firstpulse and a negative-voltage pulse in the second pulse. The AD drivesignal VcomAC shown in FIG. 28A is a signal in which the pulse intervalbetween two pulses shown in FIG. 27A is “0” (zero).

Furthermore, in the above respective embodiments and so on, for example,the drive electrodes COML are formed on the TFT substrate 21 and thepixel electrodes 22 are formed thereon through the insulating film 23 asshown in FIG. 6, however, the present disclosure is not limited to theabove. It is also preferable that the pixel electrodes 22 are formed onthe TFT substrate 21 and the drive electrodes COML are formed thereonthrough the insulating film 23 instead of the above.

Additionally, the liquid crystal display device using lateral-electricfield mode liquid crystal such as FFS or IPS is integrated with thetouch detection device in the above respective embodiments and so on,however, it is also preferable that liquid crystal display devices usingliquid crystal of various modes such as TN (Twisted Nematic), VA(Vertical Alignment), ECB (Electrically Controlled Birefringece) can beintegrated with the touch detection device. When such liquid crystal isused, the display device with the touch detection function can beconfigured as shown in FIG. 29. FIG. 29 shows an example of across-sectional structure of a relevant part of a display device with atouch detection function 10E according to the modification example,showing a state where a liquid crystal layer 6B is sandwiched between apixel substrate 2B and a counter substrate 3B. Names and functions ofother respective portions are the same as the case of FIG. 6, theexplanation is omitted. The example differs from the case of FIG. 6 in apoint that the drive electrodes COML used as both for display and fortouch detection are formed on the counter substrate 3B.

The capacitance-type touch detection device is applied as an example inthe above respective embodiment, however, the present disclosure is notlimited to this, and for example, an optical type or a resistive typedevice can be also applied instead of the above.

The liquid crystal device is used as the display device as an example inthe above respective embodiments, however, the present disclosure is notlimited to this, and for example, an EL (Electroluminescence) device canbe also applied instead of the above.

The present disclosure may be implemented as the followingconfigurations.

-   (1) A display apparatus including-   a display device,-   a touch detection device, and-   a driver unit driving the display device so as to sequentially    display M horizontal lines in each of plural unit drive periods    forming one frame period and driving the touch detection device in N    touch detection periods provided in each unit drive period, in which    N is lower than M.-   (2) The display apparatus described in the above (1),-   in which the driver unit drives the touch detection device before    displaying each of N horizontal lines in M horizontal lines in each    unit drive period.-   (3) The display apparatus described in the above (1) or (2),-   in which the touch detection device has-   drive electrodes, and-   touch detection electrodes forming capacitance between the touch    detection electrodes and the drive electrodes, and-   the driver unit applies an AC drive signal which makes a transition    once or more in each touch detection period to the drive electrodes.-   (4) The display apparatus described in the above (3),-   in which the AC drive signal has one or plural pulses.-   (5) The display apparatus described in the above (4),-   in which a pulse width of the AC drive signal in one touch detection    period is different from a pulse width of the AC drive signal in    another touch detection period.-   (6) The display apparatus described in the above (4) or (5),-   in which a pulse position of the AC drive signal in one touch    detection period is different from a pulse position of the AC drive    signal in another touch detection period.-   (7) The display apparatus described in any one of the above (3) to    (6), further including-   a detection unit sampling a detection signal outputted from the    touch detection electrodes at timings before and after respective    transitions of the AC drive signal to detect a touch based on    variations in sampling results in respective transitions.-   (8) The display apparatus described in any one of the above (1) to    (7),-   in which the “N” is 1.-   (9) The display apparatus described in any one of the above (1) to    (8),-   in which a turn in which one horizontal line is display-driven in    the unit drive period to which one horizontal line belongs in one    frame period is different from a turn in which one horizontal line    is display-driven in the unit drive period to which one horizontal    line belongs in another frame period.-   (10) The display apparatus described in any one of the above (3) to    (7),-   in which the driver unit applies the AC drive signal in units of a    given number of respective drive electrodes.-   (11) The display apparatus described in the above (10),-   in which the driver unit applies the AC drive signal to the same    drive electrodes over a given number of unit drive periods.-   (12) The display apparatus described in any one of the above (3) to    (7),-   in which the display device includes-   a liquid crystal layer, and-   pixel electrodes formed between the liquid crystal layer and the    drive electrodes or arranged opposite to the liquid crystal layer so    as to sandwich the drive electrodes.-   (13) The display apparatus described in any one of the above (3) to    (7),-   in which the display device includes-   a liquid crystal layer, and-   pixel electrodes arranged opposite to the drive electrodes so as to    sandwich the liquid crystal layer.-   (14) The display apparatus described in the above (12) or (13),-   in which the driver unit applies a display drive signal to the drive    electrodes in periods other than the touch detection period.-   (15) A drive circuit including-   a driver unit driving a display device so as to sequentially display    M horizontal lines in each of plural unit drive periods forming one    frame period and driving a touch detection device in N touch    detection periods provided in each unit drive period, in which N is    lower than M.-   (16) A driving method including-   driving a display device so as to sequentially display M horizontal    lines in each of plural unit drive periods forming one frame, and-   driving a touch detection device in N touch detection periods    provided in each unit drive period, in which N is lower than M.-   (17) An electronic apparatus including-   a display apparatus, and-   a control unit performing operation control using the display    apparatus,-   in which the display apparatus has-   a display device,-   a touch detection device, and-   a driver unit driving the display device so as to sequentially    display M horizontal lines in each of plural unit drive periods    forming one frame period and driving the touch detection device in N    touch detection periods provided in each unit drive period, in which    N is lower than M.

It should be understood that various changes and modifications to thepresently preferred embodiments described herein will be apparent tothose skilled in the art. Such changes and modifications can be madewithout departing from the spirit and scope of the present subjectmatter and without diminishing its intended advantages. It is thereforeintended that such changes and modifications be covered by the appendedclaims.

The invention is claimed as follows:
 1. A display device comprising: adisplay function layer; pixel electrodes arranged in a row-columnconfiguration; drive electrodes overlapping the pixel electrodes; adriver unit configured to the drive the pixel electrodes and the driveelectrodes to display images and to detect a touch; and a control unitconfigured to cause the driver unit to: divide a frame in which an imageis displayed by all of the pixel electrodes into a plurality of displayperiods, the display period being a period in which the drive electrodesare driven as a common electrode to the pixel electrodes: and provide atouch period between the display periods, the touch detection periodbeing a period in which the drive electrode is driven to detect a touch,wherein the driver unit is further configured to: during the displayperiod, apply a DC drive signal as the common signal to all the driveelectrodes, during the touch period, apply an AC driving signal to thedrive electrode, the AC signal applied in a first touch period isdifferent from the AC signal applied in a second touch period next tothe first touch period.
 2. The display device according to claim 1,wherein the AC signal includes at least a pulse signal, the width of thepulse signal in the first touch period is different from that in thesecond touch period.
 3. The display device according to claim 1, whereinthe AC signal includes at least a pulse signal, the timing of the pulsesignal in the first touch period is different from that in the secondtouch period.
 4. The display device according to claim 1, wherein the ACsignal includes at least a pulse signal, and at least two of the width,and the timing of the pulse signal in the first touch period isdifferent from those in the second touch period.
 5. The display deviceaccording to claim 1 further comprising: scanning signal lines extendingin a line direction and being arranged in a column direction whichintersects the line direction; pixel signal lines extending in thecolumn direction and being arranged in the line direction; and switchelements, each of the switch elements being electrically coupled to oneof the gate lines and one of the signal lines, wherein each of the pixelelectrodes is electrically coupled to one of the switch elements, andwherein the driver unit is configured to cause the scanning signallines, the pixel signal lines, and the drive electrodes to displayimages and to detect a touch.
 6. The display device according to claim5, wherein the driver unit is further configured to: during the displayperiod, apply a scanning signal to the scanning signal line sequentiallyto activate the switch elements of a target of the display operation,and apply pixel signals to the pixel signal lines to supply the pixelsignals to the pixel electrode through the switch elements respectively;and during the touch period, apply the AC driving signal to the driveelectrode to be a target.
 7. The display device according to claim 1,wherein during the touch period the driver unit is further configured toapply an AC driving signal to the drive electrode to be a target of thetouch detection operation, apply a DC drive signal to the rest of thedrive electrodes, and not apply the scanning signal to all scanningsignal lines to inactivate all the switch elements.
 8. The displaydevice according to claim 1, wherein the AC drive signal has at leastone pulse.
 9. The display device according to claim 8, wherein a numberof the pulses during the touch detection period is less than number ofthe gate signals during the display period next to the touch detectionperiod.
 10. The display device according to claim 8, wherein a number ofthe pulses during the touch detection period is equal to a number of thegate signals during the display period next to the touch detectionperiod.
 11. The display device according to claim 8, wherein a number ofthe pulses during the touch detection period is more than a number ofthe gate signals during the display period next to the touch detectionperiod.
 12. The display device according to claim 1, further comprisinga liquid crystal layer, wherein the pixel electrodes are formed betweenthe liquid crystal layer and the drive electrodes.
 13. The displaydevice according to claim 12, further comprising touch detectionelectrodes above the drive electrodes, wherein capacitances are formedbetween the touch detection electrodes and the drive electrodesrespectively. 14 The display device according to claim 13, wherein thedrive electrodes lengthen in one direction of the column direction andthe line direction, and the touch detection electrodes lengthen in otherdirection.
 15. The display device according to claim 1, furthercomprising a liquid crystal layer, wherein the pixel electrodes arearranged opposite to the drive electrodes so as to sandwich the liquidcrystal layer.
 16. The display device according to claim 15, furthercomprising touch detection electrodes above the drive electrodes,wherein capacitances are formed between the touch detection electrodesand the drive electrodes respectively.
 17. The display device accordingto claim 16, wherein the drive electrodes lengthen in one direction ofthe column direction and the line direction, and the touch detectionelectrodes lengthen in other direction.